PB2461: CONDITIONING REGIMEN AND SUBPOPULATION COMPOSITION OF AUTOGRAFT LYMPHOCYTES IN PATIENTS WITH MULTIPLE MYELOMA
Authors: Ivan Kostroma, Tatjana Glazanova, Zhanna Chubukina, Ruzilja Sabitova, Irina Pavlova, Stanislav Bessmeltsev, Sergey Sidorkevitch, Sergey Gritsaev
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: Preparation of an autograft involves obtaining at least 2x106 CD34+ cells/kg of the patient’s weight. The choice of the optimal mobilization regimen for each patient with multiple myeloma (MM) involves an assessment of the patient’s condition, disease status, volume and nature of previous therapy. For mobilization, combinations of cytostatic drugs with granulocyte colony-stimulating factor (G-CSF), G-CSF alone or in combination with plerixaphor are used. An assumption was made about the influence of the content of individual subsets of lymphocytes in the autograft on the course of MM in the post-transplant period. Aims: To evaluate the effect of mobilization modes on the composition of lymphoid subsets in the autograft of MM patients. Methods: Individual subsets of lymphocytes in the apheresis products of 25 MM patients were analyzed. G-CSF in mono mode (group 1, n=12), vinorelbine in combination with G-CSF (group 2, n=9) and cyclophosphamide at a dose of 3 g/m2 in combination with G-CSF (group 3, n=4) were used as mobilization regimens. Autologous hematopoietic stem cell transplantation (AutoHSCT) was performed in 12, 7 and 4 patients, respectively. For pre-transplant preparation, the Mel200, Mel140 regimens and the combination of melphalan with carfilzomib were used in 7/3/2, 3/0/4 and 4/0/0 patients, respectively. All patients received G-CSF in the post-transplant period, except for 1 patient in group 1. Results: A significant difference was found in the content of CD3+ cells, the percentage of which was significantly higher when using cyclophosphamide compared to G-CSF in mono mode: 91.4% vs 77.6%; p=0.029. On the contrary, the content of CD3-CD8+ cells was the lowest with the appointment of cyclophosphamide compared with the other two modes of mobilization: 0.3% vs 3.6% with G-CSF alone; p=0.045 and 0.3% vs 1.5% for vinorelbine; p=0.016. There were also significantly fewer NK cells (CD3-CD16+): 1.65% vs 10.4% with G-CSF mono. Engraftment of leukocytes and platelets in the studied groups was recorded on days 12 (9–26), 11 (10–17), 12.5 (11–16) and on days 18 (13–28), 16 (13–20), 16.5 (12–22), respectively. Six (50%), 3 (42.9%) and 2 (50%) patients in the studied groups, respectively, required transfusion of donor red blood cells. All patients received transfusions of platelet concentrate, the median number of doses in the groups was 5 (1–16), 4 (2–7) and 5 (2–7), respectively. Before AutoHSCT, all patients received bortezomib, carfilzomib – 3 (25%), 5 (55.6%) and 2 (50%) patients, respectively, lenalidomide – 1 (8.3%), 2 (22.2%) and 3 (75%), respectively, and daratumumab – 2 (16.7%), 2 (22.2%) and 4 (100%), respectively. The number of patients treated with daratumumab was significantly higher in group 3 compared to group 1; p=0.029. Summary/Conclusion: The data of the pilot study indicate a difference in the composition of lymphocytes in the apheresis product under different modes of mobilization. It is possible that the immune cell composition depends not only on the type of mobilization regimen, but also on the nature of the previous mobilization therapy, which needs to be confirmed with more data. Keywords: Multiple myeloma, Autologous hematopoietic stem cell transplantation, Autograft